Question

(such language holds the solemn sea
to the sands upon the shore)
shall bloom the thunder - blasted tree
or the stricken eagle soar!

and all my days are trances,
and all my nightly dreams
are where thy grey eye glances,
and where thy footstep gleams -
in what ethereal dances,
by what eternal streams.

what theme of the poem does the final stanza reveal?
daydreams and nighttime dreams are hard to escape.
it is difficult to concentrate when one is mourning.
dreams allow people to travel to exotic lands.
the dead are constantly remembered by those who mourn.

Explanation:

The stanza mentions that all days are trances and all dreams are filled with the memory of someone (implied as a deceased person through the mourning - like context). It shows that the mourner is constantly reminded of the dead in both day (trances) and night (dreams).

Answer:

The dead are constantly remembered by those who mourn.